Heusinger, Daniel, authorMiller, Benjamin, advisorMelby, Christopher, advisorHamilton, Karyn, committee memberMelanson, Ed, committee memberHickey, Matthew, committee member2007-01-032007-01-032011http://hdl.handle.net/10217/70362We have previously shown that in older adults, consumption of protein immediately after aerobic exercise, rather than earlier in the day, enhances nitrogen balance when energy balance is maintained. Since some older individuals consume lower calorie diets, it is important to know if these benefits also occur during hypocaloric feeding. The purpose of the study was to investigate if consumption of protein immediately after aerobic exercise rather than earlier in the day can improve nitrogen balance in older individuals consuming a hypocaloric diet. In a randomized crossover design, healthy sedentary male (n=2; age=67.0±1.0 years; BMI=27.4±0.3 kg/m²) and female (n=8; age=63.0±1.8 years; BMI=22.3±0.6 kg/m²) subjects completed two separate 3-day exercise and nutrition interventions. Exercise (60 minutes of stationary cycling at 55% of VO2max) was performed daily. Diets were hypocaloric (-15% daily intake), with a protein+carbohydrate (PRO+CHO) or carbohydrate only (CHO) drink consumed in the morning and the opposite drink consumed after exercise. Both diets (15% protein, 30% fat, and 55% carbohydrate) were isonitrogenous and isocaloric with only the timing of the drinks differing. A 24-hour stay in a metabolic chamber confirmed negative energy balance, while 24-hour urine collections determined nitrogen balance. The 3-day mean nitrogen balance was not significantly greater in the PRO+CHO trial (0.097±0.526g N) trial than the CHO trial (-0.070 ±0.520g N) (p=0.280). Thus, older individuals in negative energy balance do not maintain a significantly more positive nitrogen balance by consuming protein after aerobic exercise as opposed to earlier in the day. These results differ from our previous work and indicate that energy balance is an important determinant of the anabolic effect of protein feeding.born digitalmasters thesesengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.Text